Wire magazines of this kind are used in winding machines of the so-called single-ring type or the so-called double-ring type operating with immediate or direct winding, since the drawing of the winding wire through a bottom slit opens the opportunity for filling winding wire into the magazine from the external side thereof in one and the same operation, i.e. with the same direction of rotation for the magazine, as the winding operation.
In a prior art winding machine known from U.S. Pat. No. 2,974,890, the wire magazine is formed by two concentric rings, each of which has a circular cross section, said rings being positioned in contact with each other with a common axis of revolution. This prior art machine has not found any application in practice, mainly due to the following disadvantages.
In order to allow a selective wire drawing, the wire diameter must be great relative to the cross-sectional dimensions of the two magazine rings.
In order to avoid an acute drawing angle whereby the wire tension will be mainly directed in a tangential direction with a risk of slipping of the wire in the bottom slit, the winding object must be centrally positioned relative to the wire magazine, as a result of which narrow limits are set for the size of toroidal members which can be wound, on one hand, said requirement resulting together with the demands to the wire diameter in inferior residual hole conditions in the winding of toroidal cores, on the other hand.
Since the magazine is opened on the external side and only limited by the upper sides of the two magazine rings, it is not possible to control the wire supply after cutting of the wire. As a result thereof, it is prescribed that the filling of wire into the magazine must be continued until the winding operation has been completed, at which time a considerable unused wire supply will be collected in the magazine and must either be return-coiled or discarded.
From applicants' international patent application No. PCT/DK79/00008, international publication No. WO 79/00763, winding machines are known, in which a wire magazine of the kind mentioned is closed on the external side either by a driving belt for rotating the wire magazine or, for a machine of the double-ring type, by a separate braking belt for the wire magazine. Through the improved control of the wire supply after cutting obtained thereby, the cutting may be performed prior to completion of the winding operation, and the winding may be finished with the wire supply remaining in the magazine after cutting.
However, the closing of the magazine requires a special design of driving or braking means for the wire magazine and, thus, is not suitable in machines in which the wire magazine is driven by rollers, such as in the case of the prior art machine described in the above mentioned U.S. patent specification. Furthermore, in the design of the magazine it must be taken into account that the walls of the magazine should provide a safe engaging abutment for the driving or braking belt, whereby it will not simultaneously be possible to fulfil the desire of an optimum residual hole condition for endless cores. In this connection, an optimum residual hole condition would mean that the residual hole remaining after winding of the core exceeds the cross-sectional area of the wire supply of the magazine with as small an amount as possible.
Moreover, in the prior art wire magazines, additional ring members of a flexible material are often required to define the bottom slit in order to achieve a sufficiently good control of the wire tension and avoid wire drawing after a chord course, whereby the construction becomes more complicated and expensive.